(c) Fig. 4.18——Corals found on Bogallua Nov. 8, 1952. (a) Photograph of Acropora (top) and Heliopora (bottom), actual size. (b) Autoradiographs of corals shown in (a). (c) Enlargement of marked area in (a), The white nodules were firmly attached to the coral Arrow indicates nodule which was broken open, showing hollow nature. Magnification, 13x. CLASSIFIED